http://www.dailymail.co.uk/news/article-2191301/20 August 2012, Avila Beach near San Luis Obispo, CANektonSampling can be a challenge…Or not…MARS 3450, 12 September, 2013NektonPart 2Sumich 1992MammalsBirdsReptilesAmphibiansOrder: CarnivoraClass: MammaliaSuperfamily: Pinnipedia•Endotherms•Body covered with hair•Bear live young, feed with milkSeals, Sea Lions, Walruses•Live primarily in cold seas•Rest and reproduce on land•Conserve heat with:BlubberThick fur that traps airLarge body sizeInsulation and buoyancyLow surface:volume ratio for heat retentionAlso some fish:large tunasSealsSea Lions and Fur Seals•External ears•Rear flippers move forward•N. Pacific and S. Hemisphere•No external ears•Rear flippers can’t move forward•Elephant seals are the largest: 4 tons•Monk seals live in warm seasSouthern Sea Lions•External ears•Rear flipper bends forwardElephant Seals•No external ears•Colonial nesting•Thick blubberCastro and Huber 2003Walrus•1 species•Rear flippers move forward•Upper canines modified to tusks•Arctic Ocean only•Feed on bottom invertebratesOther pinnipeds feed on fish and planktonWalrus FeedingOrder: CarnivoraClass: MammaliaSuperfamily: Musteloidea•Smallest marine mammal (60 lbs)•Hind feet are modified flippers•Can mate and reproduce in the water•No blubber; rely on thick fur•Feed on urchins, crabs, mussels, fish•Coastal N. Pacific, from CA to AKSea OttersOrder: CarnivoraClass: MammaliaSuperfamily: Ursoidea•Native to the Arctic•Closely related to Grizzly Bear•Adult males weigh up to 1400 lbs•Dependent on sea ice for food •Feeds primarily on seals•Delayed maturation, small litters•~25,000 individuals remain, decliningPolar BearsOrder: CarnivoraClass: MammaliaPolar Bears in a Warming Climate•Accelerating decrease in extent of sea ice•Remaining sea ice is over deeper water•Dependent on sea ice •Poor ice cover = poor feeding, fat storage, reproduction•Increased distance to preferred denning areas•Fragmented ice requires more swimming•Prey populations adversely affectedDerocher et al. 2004Hudson Bay:Loss of 0.9 kg/day during fastingAverage pregnant female = 283 kgNo reproduction below 183 kg20051979-2004 average2012Summer 2012 Winter 2012Lowest coverage on recordGreater than average coveragePolar Bear FeedingSumich 1992MammalsBirdsReptilesAmphibiansOrder: SireniaClass: Mammalia•Restricted to tropical waters•Sexual maturity >10 yrs•Lifespan up to 80 yrs•Length: 2-3 m•Have lost rear pair of limbs•Reproduce in the water•Swim with strokes of paddle-shaped tail•Only herbivorous marine mammal;feeds on seagrasses, aquatic plantsManatees and DugongsManatees have rounded tails, dugongs have fluked tails like whales.They have different numbers of vertebrae in their necks, and some manatees have nails on their flippers.Milne 1995Order: SireniaClass: Mammalia•Three species of manateeAmazon (freshwater)Florida/CaribbeanWest Africa•One species of dugongIndo-Pacific•One extinct species:Stellar Sea Cow 8 m longAnd last, but not least…http://www.dailymail.co.uk/news/article-2191301/Humpback whale feeding on plankton, Avila Beach CAhttp://www.dailymail.co.uk/news/article-2191301/Keep your distance: U.S. federal guidelines warn observers to stay at least 100 yards away from whales or risk being fined $50,000. Despite the massive size of the marine mammals and the risk of being fined, onlookers hovered around the feeding site coming just feet away from a whalehttp://www.dailymail.co.uk/news/article-2191301/Castro and Huber 2003Order: CetaceaClass: Mammalia•Most complete return to the water•Streamlined bodies, resemble fishbut breathe air, are endotherms, etc.•Tail (flukes) are horizontal•Lost their rear limbs•Nostrils migrated to top of head•BlubberCastro and Huber 2003Suborder:OdontocetiSuborder: MysticetiOrder: CetaceaBaleen WhalesToothedWhalesSuborder: MysticetiFin whaleBowhead whaleOrder: Cetacea•Plates of baleen replace teeth•11 species•Largest: Blue whale; 30 m and 200 tons•Blow hole with two openings•Three feeding strategies:Skimming (Bowhead, Right)Gulping water (Fin, Blue, Humpback; “Rorqual Whales”)Bottom suctioning (Gray)Baleen WhalesCastro and Huber 2003•Hair-like bristles on inside of baleen form a dense mat•Gulp of water is pushed through baleen when tongue is raised•Bristles screen food from water•Whales lick food from bristlesSkimmingGulpingLevinton 2001Right WhaleBlue Whalehttp://www.dailymail.co.uk/news/article-2191301/Blue Whales•Size•Streamlined body•Pleated lower jaw•Concentrations of preyA. Genin et al., Science 308, 860 -862 (2005) Baleen whales find sufficient food because copepods and krill form dense patchesBut how do these patches form?Zooplankton swim to exactly counteract the water movement that would disperse themSophisticated new acoustic instrument can look at very small scalesMaybe they sense pressure.Maybe their food is concentrated there; maybe their mates are. How?Why?Northern Right WhaleFujiwara and Caswell. 2001. Nature 414:537.•Cape Cod to GA, FL•Increased numbers after whaling ban•But decreased since 1997•300 individuals remain•Population decline due to Allee effect?•Decline due to early female death•2-3 fewer female deaths would allow recovery•New NMFS regulations are helpingAverage female lifespan: 15 yearsSexual maturity: 10 yearsGive birth: every3-5 yearsOrder: CetaceaeSuborder: OdontocetiKiller whaleSperm whaleSpinner dolphin•Use teeth to grab prey; swallow whole•80 species•Largest: Sperm whale•Blow hole with one opening•Dolphins, porpoises highly social•Family groups = ‘pods’Toothed WhalesGray Whales and Orcas•Contrast feeding strategies•Social behavior of Orcas•Importance of access to surfaceSwimmingSo how do they do it?Adaptations of marine mammals• Streamlined for efficient swimming: body shape, loss of rearlimbs, loss of external ears, loss of hair on body• Rapid breathing: 2 seconds to empty and refill lungs• Hold air for 30 seconds between breaths, extract 90% of O2• More red blood cells• More hemoglobin per cell• Muscles rich in myoglobin• Nostrils on top of head: breathe while most of animal is below waterTakes humans twiceas long for 1/3000thof volumeStore oxygenDivingAdaptations of nektonic organisms: mammals•Dives last from 4 min (sea otters) to 1 h (sperm whale)•Increased oxygen storage•Bradycardia: slowing of heart